The tar in this poem looks like a metaphor for something harmful that feels good at first, though the poem never says what it stands for. Addiction is one reading, and a destructive comfort or habit is another. The speaker begins cautiously, with just a toe, and finds the tar warm and welcoming. Each stanza goes deeper: hips, then neck. The comfort grows, but so does the danger.
The speaker's feelings shift along the way. Curiosity turns into ease, then into a kind of dependence. Mentions of "scorching guilt" suggest the speaker knows something is wrong, yet keeps going anyway. The images turn darker too, from a nostalgic hug to a starving snake swallowing its prey. By the end, the speaker is "fond / Of being burned alive."
The mood is seductive and unsettling at once. The calm, steady tone makes the ending more disturbing, because the speaker never panics. Being consumed is described almost like love.